Cat tree



FIG. 1 is a front view of a cat tree, showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a bottom plan view thereof;

FIG. 4 is a rear plan view thereof;

FIG. 5 is a left plan view thereof;

FIG. 6 is a right plan view thereof; and,

FIG. 7 is a perspective view thereof.

The broken lines in the drawing depict portions of the cat tree that form no part of the claimed design. 

CLAIM The ornamental design for a cat tree, as shown and described. 